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<p class="level0"><a name="NAME"></a><h2 class="nroffsh">NAME</h2>
<p class="level0">CURLOPT_SOCKOPTFUNCTION - set callback for setting socket options <a name="SYNOPSIS"></a><h2 class="nroffsh">SYNOPSIS</h2>
<p class="level0"><pre class="level0">
&#35;include &lt;curl/curl.h&gt;
&nbsp;
typedef enum  {
&nbsp; CURLSOCKTYPE_IPCXN,  /* socket created for a specific IP connection */
&nbsp; CURLSOCKTYPE_ACCEPT, /* socket created by accept() call */
&nbsp; CURLSOCKTYPE_LAST    /* never use */
} curlsocktype;
&nbsp;
&#35;define CURL_SOCKOPT_OK 0
&#35;define CURL_SOCKOPT_ERROR 1 /* causes libcurl to abort and return
&nbsp;                               CURLE_ABORTED_BY_CALLBACK */
&#35;define CURL_SOCKOPT_ALREADY_CONNECTED 2
&nbsp;
int sockopt_callback(void *clientp,
&nbsp;                    curl_socket_t curlfd,
&nbsp;                    curlsocktype purpose);
&nbsp;
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
</pre>
<a name="DESCRIPTION"></a><h2 class="nroffsh">DESCRIPTION</h2>
<p class="level0">Pass a pointer to your callback function, which should match the prototype shown above. 
<p class="level0">When set, this callback function gets called by libcurl when the socket has been created, but before the connect call to allow applications to change specific socket options. The callback's <span Class="emphasis">purpose</span> argument identifies the exact purpose for this particular socket: 
<p class="level0"><span Class="emphasis">CURLSOCKTYPE_IPCXN</span> for actively created connections or since 7.28.0 <span Class="emphasis">CURLSOCKTYPE_ACCEPT</span> for FTP when the connection was setup with PORT/EPSV (in earlier versions these sockets weren't passed to this callback). 
<p class="level0">Future versions of libcurl may support more purposes. libcurl passes the newly created socket descriptor to the callback in the <span Class="emphasis">curlfd</span> parameter so additional setsockopt() calls can be done at the user's discretion. 
<p class="level0">The <span Class="emphasis">clientp</span> pointer contains whatever user-defined value set using the <a Class="emphasis" href="./CURLOPT_SOCKOPTDATA.html">CURLOPT_SOCKOPTDATA</a> function. 
<p class="level0">Return <span Class="emphasis">CURL_SOCKOPT_OK</span> from the callback on success. Return <span Class="emphasis">CURL_SOCKOPT_ERROR</span> from the callback function to signal an unrecoverable error to the library and it will close the socket and return <span Class="emphasis">CURLE_COULDNT_CONNECT</span>. Alternatively, the callback function can return <span Class="emphasis">CURL_SOCKOPT_ALREADY_CONNECTED</span>, to tell libcurl that the socket is already connected and then libcurl will not attempt to connect it. This allows an application to pass in an already connected socket with <a Class="emphasis" href="./CURLOPT_OPENSOCKETFUNCTION.html">CURLOPT_OPENSOCKETFUNCTION</a> and then have this function make libcurl not attempt to connect (again). <a name="DEFAULT"></a><h2 class="nroffsh">DEFAULT</h2>
<p class="level0">By default, this callback is NULL and unused. <a name="PROTOCOLS"></a><h2 class="nroffsh">PROTOCOLS</h2>
<p class="level0">All <a name="EXAMPLE"></a><h2 class="nroffsh">EXAMPLE</h2>
<p class="level0">TODO <a name="AVAILABILITY"></a><h2 class="nroffsh">AVAILABILITY</h2>
<p class="level0">Added in 7.16.0. The <span Class="emphasis">CURL_SOCKOPT_ALREADY_CONNECTED</span> return code was added in 7.21.5. <a name="RETURN"></a><h2 class="nroffsh">RETURN VALUE</h2>
<p class="level0">Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. <a name="SEE"></a><h2 class="nroffsh">SEE ALSO</h2>
<p class="level0"><a Class="manpage" href="./CURLOPT_SOCKOPTDATA.html">CURLOPT_SOCKOPTDATA</a>, <a Class="manpage" href="./CURLOPT_OPENSOCKETFUNCTION.html">CURLOPT_OPENSOCKETFUNCTION</a><p class="roffit">
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